Just made this sectional following the plans from Ana White.
Roughly $900 CAD in materials, $750 of that being the cushions. I used Duvholmen cushions with Jarpon covers from Ikea, accent pillows I found at Home Sense. All 2x4 lumber and I used pocket holes where screws would be visible. Finished with Ready Seal natural cedar.
Quite happy with it overall. It's really comfortable and will last far longer than (and was cheaper than) those plastic weave ones from big box stores.
Yeah I looked around a bit and there were a few cheaper options on amazon and things, but it's difficult to tell the quality on those. I knew I'd get something reasonable from Ikea, that the cushions would actually be more or less the size they claim, they'd be built for the outdoors, and that the covers would fit them perfectly.
Even the alternatives I found weren't a whole lot cheaper. I'm happy with the quality of these at $125/seat.